I saved us $$$
When the technician was here for our annual furnace inspection he noticed the heat exchanger was going bad. Said the company would get back to us about either replacing it or with an estimate for a new furnace. This furnace is only ten years old, so figured they'd replace the part. We were shocked when they sent an estimate of almost $3,000 to replace the furnace.
Luckily I save every manual and piece of information on appliances and anything else that comes with a warranty. Dug out the information and sure enough there is a life time limited warranty on the heat exchanger. Soo I called the company and after much searching of the unit found the serial number for the part and TA-DA! Yep, it's covered. So called the company and give them the information.
Long story short we're only going to have to shell out around $500 versus nearly $3,000.00
So glad I decided to check this out versus just saying "Oh heck, guess we need to get a new furnace".